When charging multi-cell battery packs each battery cell must not be over or under charged. This requires charge balancing of the multi-cell battery pack. There are four different methods for charge balancing of a multi-cell Battery Pack: 1) FIG. 6 shows a resistive charge balancing circuit that is used to discharges cells having a higher voltage until they match the charge voltage of lower voltage cells to balance the charge between the cells. 2) FIG. 7 shows a capacitive charge shuttling circuit used for moving charge from battery cell(s) having a higher voltage to battery cell(s) having a lower voltage. 3) FIG. 8 shows an inductive charge shuttling circuit used for moving charge from battery cell(s) having a higher voltage to battery cell(s) having a lower voltage. And 4) FIG. 9 shows an inductive switching system that takes charge from higher voltage battery cells and dumps the charge back into the full battery pack. Each of these methods removes charge from lower capacity batteries to charge higher capacity cells. The repeated charge/discharge reduces battery life and increases the losses in wasted energy during the battery charging balancing process.
There are two main problems with the aforementioned battery charging methods: One, existing charge balancing methods result in a reduction of charge life typically expected with the individual battery cells. Two, existing charge balancing systems move charge already in a cell, to another cell resulting in losses due to the internal resistance of the cell.